Add mouse support for Linux curses build

Most mouse functionality has been enabled, however mouse support in curses depends on what events the host terminal passes down to the program.

Some terminals will capture the right mouse button for their own context menu and not send this event to programs... right clicking won't work for the game in these terminals, unless you can disable its context menu.

Mouse move events may not be detectable by default. If that's the case, you can try:
export TERM=xterm-1002

and if that doesn't work:
export TERM=xterm-1003

One of those settings ought to get mouse move events firing.

The scroll-wheel doesn't seem to work well at all in curses, at least on my Linux VM. The wheel movements are detected, but they get interpreted with random IDs, triggering other events. So I disabled that for now. Maybe someone else can take a deeper look.